big bore kit for vfr700

Discussion in 'Mechanics Garage' started by fatso1277, May 8, 2008.

  1. fatso1277

    fatso1277 New Member

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    anyone have any ideas or engine mods to a vfr700. i found the kit for the 750, but looking for something EXTRA for the 700...many upgrades planned so while the engine is out wanna take care of engine, got jet kit planned and thats about it. any other suggestions for MORE POWER...(outside of a new bike)
     


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  2. XRayHound

    XRayHound New Member

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    I think the best plan is to find a 750 engine and swap it in, then start modifying that. That's what I'm going to do... sooner or later.
     


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  3. fatso1277

    fatso1277 New Member

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    are the mounting holes the same for the 700 as they are for the 750.
     


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  4. Chris71Mach1

    Chris71Mach1 Member

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    daaaaaaaaaaamn that. the differences between the 86 and 87, though nominal, are enough to justify not jacking around with swapping years. there is a set of overbore pistons that will fit in these motors though. consider first that the 86's and 87's, be they 700 or 750, all use the same 70mm pistons. the extra 50cc in the 750's are made with a longer stroke in the crankshaft, making the crank and the connecting rods the big differences in the rotating assemblies between the 700 and 750.

    if you want to just throw the overbore kit into the 700 motor, that would be fine an dandy, youd just have to bore your cylinders out by the necessary 4mm to accomodate the big bore pistons, which would give you roughly 790cc of displacement. not the 840 that the 750 would see, but still not too shabby.

    my solution (and the next project that im going to undertake after I complete my suspension overhaul project) will be to maintain my 87 model engine cases, swap in a crank and connecting rods from the 86 model 750, and then have the cylinders bored out and plug in that set of big bore pistons, effectively upgrading the 700 motor to the full on 840.

    this way i wont have to jack around with swapping the black box, messing with teh cam pulse generator, or any wierdness like that. itll all be 87 stuff (well, most ;) )
     


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